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   难度：Easy
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   <h1 class="question_title">
    342. Power of Four
   </h1>
   <p>
    Given an integer (signed 32 bits), write a function to check whether it is a power of 4.
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   <p>
    <strong>
     Example 1:
    </strong>
   </p>
   <pre>
<strong>Input: </strong><span id="example-input-1-1">16</span>
<strong>Output: </strong><span id="example-output-1">true</span>
</pre>
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    <p>
     <strong>
      Example 2:
     </strong>
    </p>
    <pre>
<strong>Input: </strong><span id="example-input-2-1">5</span>
<strong>Output: </strong><span id="example-output-2">false</span></pre>
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   <p>
    <b>
     Follow up
    </b>
    : Could you solve it without loops/recursion?
   </p>
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   <h1 class="question_title">
    342. 4的幂
   </h1>
   <p>
    给定一个整数 (32 位有符号整数)，请编写一个函数来判断它是否是 4&nbsp;的幂次方。
   </p>
   <p>
    <strong>
     示例 1:
    </strong>
   </p>
   <pre><strong>输入: </strong>16
<strong>输出: </strong>true
</pre>
   <p>
    <strong>
     示例 2:
    </strong>
   </p>
   <pre><strong>输入: </strong>5
<strong>输出: </strong>false</pre>
   <p>
    <strong>
     进阶：
    </strong>
    <br>
    你能不使用循环或者递归来完成本题吗？
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